Ruby through 2.2.7, 2.3.x through 2.3.4, and 2.4.x through 2.4.1 can expose arbitrary memory during a JSON.generate call. The issues lies in using strdup in ext/json/ext/generator/generator.c, which will stop after encountering a '\0' byte, returning a pointer to a string of length zero, which is not the length stored in space_len.
https://www.ruby-lang.org/en/news/2017/09/14/ruby-2-3-5-released/
https://www.ruby-lang.org/en/news/2017/09/14/ruby-2-2-8-released/
https://www.debian.org/security/2017/dsa-3966
https://usn.ubuntu.com/3685-1/
https://security.gentoo.org/glsa/201710-18
https://lists.debian.org/debian-lts-announce/2018/07/msg00012.html
https://github.com/flori/json/commit/8f782fd8e181d9cfe9387ded43a5ca9692266b85
https://bugs.ruby-lang.org/issues/13853
https://access.redhat.com/errata/RHSA-2018:0585
https://access.redhat.com/errata/RHSA-2018:0583
https://access.redhat.com/errata/RHSA-2018:0378
https://access.redhat.com/errata/RHSA-2017:3485
http://www.securitytracker.com/id/1042004